1. Field of the Invention
This invention relates to an orginal keep device for the original carriage of copying machine.
2. Description of the Prior Art
Original keep devices according to the prior art are illustrated in FIGS. 1 to 3 of the accompanying drawings. FIG. 1 shows a copying machine provided with an original keep device of the prior art.
On top of the machine housing 1, a movable original carriage 3 may be guided along rails 7 and 7'. To produce a copy, an original keep plate 4 of flexibility formed of rubber or similar material which is disposed on top of the original carriage 3 may be raised or opened (as indicated by dots-and-dash lines in FIG. 1) by manually gripping a handle 8 thereof, whereafter an original may be placed in position beneath the keep plate with its image-bearing surface facing down and then the original keep plate 4 may be lowered or shut to its initial position, whereafter a copy button 5 may be depressed. The original carriage 3 will automatically reciprocate horizontally and a copy will be discharged onto a tray 6.
The original keep plate 4 has one end thereof secured to the original carriage 3 by means of hinges 2 and 2'. Such an original keep device is very simple in construction and requires only a few parts and thus a lower cost. This system, however, requires the operator to grip and raise the original keep plate with his right hand while placing an original with his left hand. Thus, the operator has to use his both hands for copying a single original, and when a plurality of different originals are to be copied in succession, only one of them must be taken and the other originals must be placed somewhere else. This means a low operability of the device to the user. In spite of such disadvantage, the simplicity of construction has contributed to employment of such system.
FIGS. 2 to 4 show a second example of the conventional device. Again, on top of the machine housing 1, a movable original carriage 3 may be guided along rails 7 and 7'. To produce a copy, an original keep plate 4 may be raised or opened by manually gripping a handle 8 thereof, an original to be copied may be placed on the carriage, the original keep plate may be lowered or shut and a copy button 5 may be depressed. The original carriage 3 will automatically reciprocate and a copy will be discharged onto a tray 6. The original keep plate 4 has one end thereof secured to the original carriage 4 by means of hinge 2. A block 10 is secured to the original keep plate 4 and formed with a hole 10.sub.3 in which one end of a support bar 9 is fitted. The other end of the support bar 9 is loosely fitted in a hole formed in the handle 8. When the original keep plate is opened beyond 90.degree. by gripping the handle 8, the keep plate tends to fall down from gravity in the opposite direction, but the back 10.sub.1 of the block 10 bears against the upper surface of the original carriage 3 to prevent any further pivoting of the original keep plate, while the support bar 9 has its counter-clockwise swing restricted with respect to the block 10 (the restriction is provided by the engagement between the support bar 9 and the bearing surface 10.sub.2 of the block 10)l, so that the original keep plate may remain open even after the handle is released. Why the support bar 9 is designed for some swinging movement with respect to the block 10 will be apparent from FIG. 4. More particularly, the reason is that even if a greatly thick original such as original 0 is placed on the carriage 3, the line passing through the hinge 2 and the block hole 10.sub.3 and the line of the support bar 9 form a wide angle to allow for reception of even such thick original.
This system is good in operability inasmuch as the keep plate 4 can remain open to leave the other hand of the user free. Such system has been employed in larger-sized copying machines.
Although not so popular, there is a third system whereby the original keep device is operatively associated with the copy button. This is an automatic system wherein depression of the copy button closes the keep plate and completion of a copy causes the keep plate to be opened. Such system involves complicated mechanical construction and has only been employed in a few of high-class copying machines.
These three systems are all of the original keep devices for copying machines, although they involve some differences in details when they are embodied. Except the third one, the first and second systems would offer problems if they were applied to large-sized copying machines because the original keep device would accordingly be larger in size and heavier in weight.
First, in case of the first system, the original keep plate would be too large and heavy to handle and hold it with a single hand, and in case of the second system, access to the keep plate when in its open position would be impossible.
Also, in the copying machines of the prior art, the original keep plate must be opened and shut for each copying operation irrespective of the size of the original to be copied, to thereby permit the original to be placed on and removed from the original carriage. In such instances, no problem in operation would be encountered in copying machines of smaller maximum copy size because the original keep device would correspondingly be smaller in size, but if the copying machines were of larger maximum copy size (say, A2 or larger size), then the original keep device would become larger and heavier and thus, would be difficult to manipulate. More specifically, the original keep plate in its open position would be difficult to manually hold and placement of the original in position on the carriage would also encounter difficulties. Further, the entire keep plate of heavy weight must be opened and shut for each copying operation irrespective of the copy size and this means an increased labor and accordingly a problem in operability of the machine on the part of the operator.
FIGS. 21a and b show the relationships of the copy sizes (areas) of formats A and B less than A2. In format A (FIG. 21a), A4 is the double size for A5, A3 is the double size for A4, and A2 is the double size for A3. In format B (FIG. 21b), B4 is the double size for B5 and B3 is the double size for B4. Thus, if the maximum copy size for the copying machine is size A2, an original of size A2 or B3 could not be set on the original carriage unless the entire original keep plate is opened, but by designing the original keep plate into a split construction so as to permit a portion thereof somewhat larger than one-half of the entire area of the keep plate to be opened and shut, originals of lesser size, i.e. A3, A4, A5, B4, B5, etc. may be set on the original carriage without the need to open the entire keep plate.